A machine of the kind referred to is known from U.S. Pat. No. 3,995,203. This known machine is constructed and combined with rectifier equipment in such a manner that the machine may function, with acceptable efficiency, either as a generator or a motor. A relatively simple rectifier equipment is used, and the material utilization of the reluctance machine need not differ much from that usually obtained with rotary electrical machines.
One condition for obtaining these advantageous properties in the known machine is that only double-pole coils are used. This involves complicated design work since the coils must be manufactured with specially shaped coil ends due to the fact that the coil ends of each coil must be constructed with regard to their position in relation to the adjacent, intersecting coil ends. Furthermore, double-pole coils are unfavourable from the point of view of operation and maintenance, since replacement of a defective coil by a new coil requires, in 50 percent of the cases, removal of at least two additional coils.
In the aforesaid U.S. Patent it is also mentioned that two single-pole coils arranged on adjacent poles may replace one double-pole coil if they are interconnected in such a way that the surrounded poles are excited in one and the same direction, i.e. so that one pair of single-pole coils becomes fully equivalent to a double-pole coil as regards the excitation effect.
However, the use of such single-pole coils would result in coil sides having opposite axial current directions in the pole gap between poles excited in the same direction. Such coil sides are of no use whatsoever since one will cancel the magnetic effect of the other. The result is a low utilization of the conductor material of the reluctance machine and at the same time an increase of the losses of the machine, because of the electrical energy which is transformed into heat in the useless, surplus conductor material.
Furthermore, the known machine requires the use of a series winding, since the working winding and the premagnetizing winding act with opposite directions in half of the poles of a working winding, and since it is desired to have a pre-magnetization in these poles which is dependent on the current intensity of the working winding in such a way that the resultant number of ampere turns of the pole may become very small but never changes direction. This series winding is an additional complication from the point of view of manufacture.
The present invention aims to provide a reluctance machine of the kind referred to in which the above-mentioned drawbacks are eliminated. In particular the invention aims to provide a reluctance machine in which the commutating conditions of the rectifying means are just as favourable as in the known machine, and in which largely the same simple principle of current supply is employed, but in which the windings of the reluctance machine are constructed in such a way that simplified manufacture and maintenance are achieved while maintaining the degree of material utilization.